


Harmonic Function

by shaenie



Category: Stargate Atlantis
Genre: BDSM, Dom/sub, M/M, Pre-Canon, hard kink
Language: English
Status: Completed
Published: 2008-05-26
Updated: 2008-05-26
Packaged: 2017-10-12 03:58:18
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 8,281
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/120500
Author URL: https://archiveofourown.org/users/shaenie/pseuds/shaenie
Summary: <blockquote class="userstuff">
              <p><em>"Let's go with Banach-Tarski as your safeword," McKay says almost absently, lips tracing lazily along John's hairline, and John blinks.</em></p>
            </blockquote>





	Harmonic Function

**Author's Note:**

> Thanks go to the usual suspects, [](http://cindyjade.livejournal.com/profile)[**cindyjade**](http://cindyjade.livejournal.com/) and [](http://the-drifter.livejournal.com/profile)[**the_drifter**](http://the-drifter.livejournal.com/), for all the usual reasons, and also to [](http://pir8fancier.livejournal.com/profile)[**pir8fancier**](http://pir8fancier.livejournal.com/) for the last minute beta, for she is the awesome. This was, probably not surprisingly, spurred into existence by Kink!Bingo, but I'm choosing not to use it for that for a couple of reasons. Nevertheless, a thank you to the ladies responsible for Kink!Bingo is in order. THANK YOU!! Also, people who do Math: I translated an equation from Math to English for the purposes of this story, and it is probably wrong wrong wrong. Feel free to help me correct it, but if you do, you're enslaved as permanent Math-Beta until the end of time. <3

1.

John goes looking for something, dressed to kill in the way that he knows works for him, tight black jeans and tight, shiny shirt with a zippable collar. He thinks of it as celebrating, and leaves the pair of silver double-bars on top of the dresser in his hotel room next to his dog tags.

John notices the guy within five minutes of being there, not because he's anything special, but because he's funny. The guy's got on worn dark brown cords and a t-shirt (which says, "science is fun," and depicts two little kids injecting a rat with something) making him the biggest freak in the room full of people wearing some truly freakish things. The only nod to the type of place he's in is a black button-up thrown over the t-shirt, which is nowhere near enough to make him blend. John wonders if he'd swapped it out from his day-wear, which was probably something in plaid.

The guy isn't cruising as far as John can tell. He's sitting at one of the tables shoved up against a wall, drinking a beer and just watching. _Probably working on his thesis in one of the behavioral sciences_ , John thinks, amused. John dismisses him from his mind, and dances with the first guy who wanders by him at the bar and grabs his ass.

Over the next couple of hours he drinks a little, dances some, but mostly just circles and circles the room, looking and not finding. He's frustrated and bored and jagged and starting to feel the pull of exhaustion from flying back stateside when there's a lull in the music, and someone says "Soldier," directly in his ear, a low, careful voice. In spite of knowing better, John's back goes straight and his chin comes up, and his most compelling desire when he whirls around and sees the freaky guy is to punch him in the goddamned face.

The guy just looks at him, head tipped slightly to one side, watching him with a kind of detached curiosity that is more than a little unsettling, as if waiting to see if John is, in fact, going to punch him in the face. When John doesn't immediately do so, he tips his head a little in the other direction, eyes gleaming in the dimness, and says, "I have a hotel room."

It doesn't sound like an order, which has always been a turn-off in John's experience, but the guy is weirdly intense. John can almost feel his eyes on him, a weird prickling awareness, and he has to force himself to smirk in response. "Good for you," he says, which, ideally, would be a great line to walk away after, but he doesn't. He just stands there, pinned in place by the guy's level gaze.

The guy tips his head a little more, and John's so fixed on his face that he jumps a little when something touches his hand.

He looks down, and it's a business card. John almost laughs out loud.

But even in the dim light, he can see the bold scribble handwritten across the card. It's a name. Underneath is a series of numbers that John's brain immediately translates as a California Driver's License number, then a slash, followed by a date of birth.

He knows his eyes are a little wide when he looks back up at the guy. _Are you crazy?_ he wants to ask, because obviously he could do a hell of a lot of damage with this kind of information. The guy is still just looking at him. "What," John asks, "No social security number?"

One corner of the guy's mouth crooks up into a little smile. "I'm Canadian," he says seriously. "There's an internet cafe two blocks north of here."

John stares at him. He doesn't have any idea what to think about a guy that tries to pick him up by giving him all his personal information and inviting John to Google him before they go have kinky sex. John hasn't done this for a while, but he's willing to bet at least a couple of fingers that this is not S.O.P. these days.

No, this guy is clearly a freak of the highest caliber.

John gives the card a closer look. Dr. Rodney McKay is the freak's name.

The name of the hotel and a room number are scrawled on the back of the card.

McKay is a young guy, a year older than John according to the card. It's hard to tell for sure. He's got light brown hair and a pointy nose, is broad-shouldered but not exactly well-muscled. A little rangy, but soft. His mouth is broad and mobile, but nothing to write home about. The most remarkable thing about him are his eyes, which are bright blue, and alive with curiosity, interest, intelligence. He's regarding John with badly concealed impatience.

He's not John's type at all.

But there's nothing else here John wants, and the guy is... interesting, maybe. Different, definitely.

"Okay," John says, and the guy smiles, wide and genuine and unexpectedly contagious. John finds himself smiling back before he realizes it.

  
2.

John lets himself into the room with the key-card Dr. Rodney McKay had pressed into his hand, and ends up pacing for twenty minutes before McKay finally shows up. He can't tell if it's nerves, anticipation, irritation, or a combination of all three.

The guy looks irritatingly calm. He kicks his shoes off just inside the door and shoves them under the side table with one foot, and strips the overshirt off and flings it across the back of a chair. He doesn't even look at John until after he turns back to the door, snagging a little 'Do not disturb' placard off the doorknob, opens it and puts the placard on the doorknob on the other side. Then he locks the deadbolt, the chain, and the bar lock. Then he turns and gives John an odd little head-bobbing nod and a grin. "Hi."

John, who had been expecting nearly anything but that, goggles for a second, and then finally manages to say, "Hey," in response.

"I'm Dr. Rodney McKay. You can call me by any of those three you like, or in any combination, although honestly, I think Dr. Rodney sounds like a child molester, myself." He gives John one of those looks from the bar, the ones that make John feel pinned in place. "You didn't go to the cafe."

"No," John says, because he doesn't see any point in lying about it.

That gets him the familiar head-tilt. "What's your name?"

"John."

"Okay, John," he says, and gives a little nod as though for emphasis. "I'd like you on your knees."

And John goes down just like that, a little surprised, maybe, but not much. Because now he's curious.

"I'm going to tell you some things, and then ask you some other things," McKay says, and his voice is just right, cool and a little distant, but also just husky enough to tell John that he appreciates John on his knees. "The first thing is that I want what I ask for. I'm not trying to trick you. If you're here for a mindfuck, then there's been a misunderstanding." He pauses as though to give John time to comment.

"Yeah, a _mind_ fuck wasn't really on my agenda, Doctor," John drawls, sardonic just to get things moving, but McKay just gives him another one of those broad, genuine smiles.

He's the weirdest top ever.

  
3.

McKay's hotel is nice, far and away better than what John had been expecting. The bed is wide and medium-hard, the floor is covered in deep-pile carpet in ash-gray, and the bathroom is palatial. John's own hotel room would fit inside it three or four times.

McKay gets himself a beer from the mini-fridge, and walks barefoot across the carpet to where John is kneeling, still fully dressed. He runs a flat hand just above John's head, grazing across the slopes and swirls of John's hair. "Your hair really threw me for a few minutes," he tells John conversationally. He does it again, closer this time, something firm enough to be not unlike petting.

"My hair," John repeats, completely lost, "threw you?"

"Yes," McKay says, his voice as soft as the hand he's still sliding along the tips of John's hair, never quite close enough to actually touch John's scalp. It feels shiveringly odd, but not bad. "You're in the military," he says, as though it's the most obvious thing in the universe, and John stiffens even though it's not like he hadn't known that McKay _knew_ that. McKay's hand abandons John's hair so he can rest one fingertip lightly between John's 6th and 7th vertebrae through John's shiny black shirt. He traces upward, smoothing over the knob of bone under skin and cloth. "There's a peculiar posture specific to the Military. You hardly ever see it on anyone else." His fingertip continues to rest lightly against John's spine.

John neither confirms nor denies.

"I was sure of it, except for the weird hair." He adds another fingertip to John's back, and rubs a small warm spot between his shoulder blades. "But it makes sense if you've been deployed." McKay doesn't seem to require confirmation. He palms John's spine between his shoulder blades, and then leans forward until John can feel the barest brush of the tip of McKay's nose against his neck. McKay just breathes there for a few seconds, warm and silent, and John feels himself relaxing slightly in spite of himself.

He relaxes further at McKay's next words. "Take off your clothes, please."

John stands and strips with military efficiency, and catches McKay watching him with a slightly smug expression as he folds them automatically. John scowls, but McKay either doesn't notice, or doesn't care.

"You've seen combat," McKay murmurs, circling around behind John, and John's back goes tight. He can't stop it.

"Is there a posture to that, too?" John asks, his voice coming harsh and taut even as he holds himself deliberately still.

"There might be," McKay says. It sounds like he's smiling. "But I was going by the scars on that one." His fingertips graze John's left side just beneath his lowest rib, then his left hip.

Impossibly, John feels his back go even straighter.

"You're a runner." He pauses. "You have very nice legs, John."

Incredibly, and despite the tension he can still feel thrumming through his body, John feels the tips of his ears go warm with pleasure. McKay rests a hand on his shoulder from behind, fingertips curling forward to rest against his collar bone, and presses lightly.

John goes back to his knees.

  
4.

"Now some questions," McKay says, and circles back around in front of John, and sinks down to the floor with his legs folded in front of him so that they're startlingly eye to eye.

John blinks at him.

McKay tips the neck of his beer at John, an offer, and John takes it and drinks. Then he drinks again, and tips it to look at the label. Alexander Keiths. Huh. After another sip, he hands it back. McKay is smiling crookedly at him.

After a few seconds, John says, "Uh, questions?"

"Ah, yes, of course," McKay agrees, and rolls the bottle between his big hands. "And it should go without saying that I'm looking for honest answers, here, but in the interest of full disclosure..." He waves a hand dismissively, but then he fixes John with a sharp look, and says, "If I think you're lying to me, I'll give you a beer and cab fare to wherever you want to go."

John bristles. "I don't need your cab fare," he grates out, narrow eyed, but McKay appears totally unaffected by his irritation. He just waves his hand again.

"Will you be staying the night?" McKay asks, watching John, gaze intent and at odds with the casual tone he's using.

"Sure?" John says, and McKay looks pleased.

"Are you allergic to anything?"

"Sulfa drugs," John tells him, a little bemused.

"Citrus," McKay replies. "Epi pens in the bathroom cabinet." John nods. "I actually had someone tell me latex, after we'd already started," he tells John, frowning and rolling his eyes, clearly still aggravated by that. "Isn't that one of those things you say right up front, assuming you've allowed yourself to be picked up specifically for kinky gay sex? Don't you immediately say: 'I'm allergic to latex, and have brought condoms of - insert designated material here - for our mutual protection'? That's why I like to have this conversation before anything else happens these days."

John's lips quirk, and it feels utterly foreign to be kneeling naked, carpet faintly tickling at his knees, and wanting to smile.

McKay, apparently King of the Non-Sequitur, asks, "Can you bend at the waist and touch your toes?"

For a second or two, John thinks McKay is kidding. He's in the _military_. Then he takes in the look on McKay's face, and merely nods an affirmative.

"I'd like to see that, please," McKay says, and John isn't surprised; he stands up and bends and rests his palms on the carpet lightly. He hears McKay's breath catch, and he murmurs, "Ah, yes. That's. Yes." When John shifts to straighten, McKay snaps, "No," short and sharp and hard, and John freezes. His cock, about three-quarters hard since McKay had put him on his knees, goes fully hard and jabs him uncomfortably in places it doesn't naturally reach.

He hears McKay stand up, and sees his pale bare feet a second later. He isn't touching John, but he's standing very close.

"Is there anything else I should know for your safety, John?" he asks, low and warm, and the short hairs on the back of John's neck stand up in response to his tone, heedless of what he's actually saying. McKay looks nothing like a predator, acts nothing like any other top John has ever fucked around with, and the sound of his voice going hot and tight is so unexpectedly arousing that John hears his own breath catch.

"No," John says hoarsely. And then he thinks about spending the night, and he says to the carpet, "I have nightmares. Sometimes I thrash, or hit people if I'm startled awake."

McKay's warm, wide hand is abruptly resting at the small of his back. "All right," McKay says. "Do you have a safeword?"

"Not-" John says, and shakes his head. "Not really."

He hasn't for a long time. He doesn't really bother remembering them afterward.

"Hrm," McKay says. His thumb sweeps across John's skin. "Let's align our parameters, shall we?" John swallows, but McKay doesn't wait for him to respond. "Are you clean?"

"Yes," John says at once.

"I'm going to touch you everywhere," McKay tells him, and John appreciates the effort to make it into something other than a question while still providing John the opportunity to pass on information, if he wants to.

He realizes he's been thinking that McKay is a novice, that maybe he has the aptitude but not much in the way of experience. Trying to explain away the oddities. But he's pretty sure that's not actually it. That this is more like... some kind of bizarre _style_ choice, or something. That he probably knows he doesn't do things like John is expecting, and just doesn't give a shit.

"Okay," John tells him, and means it. Almost as soon as the second syllable is out of his mouth, McKay slides a fingertip down the crack of his ass, slow and light, exploratory, and presses lightly behind his balls. John forces himself to breathe deeply and slowly, but his skin feels like it's buzzing like a tuning fork, reacting to a frequency above John's audible range. There's a slick patch of skin just under his solar plexus where the head of his cock is sliding along skin, and he's starting to feel the strain of this position in the backs of his thighs and along either side of his spine.

"Rest now," McKay says, and John straightens, twists a little to ease some of the tightness in his back, and sinks to his knees again. McKay doesn't sit down this time. He doesn't step back, either. If John were to turn his head twenty degrees or so, he could tip his forehead against McKay's thigh in his weird worn cords. McKay slides a hand through John's hair again, firmer than before, and John feels the muscles in his neck wanting to go loose, feels his eyelids try to sag closed.

"Let's call this portion of the festivities word-association," McKay murmurs, fingertips digging into John's scalp a little, firm and gentle pressure that makes John's head want to roll forward on his neck. "Breath-play."

"Wary," John says honestly, and wonders about the texture of McKay's worn cords against his face, wonders a little about himself for wondering, but doesn't let himself think too much about it.

McKay makes a humming sound. "Bondage?"

"Sure," John says

"Nipples?"

"Disappointing."

"Non-permanent marks?"

"Hot."

"Cock-sucking?"

"Please," John says, and McKay huffs out a little laugh that makes John's face hot.

"This is aligning our parameters?" John asks, and then before he thinks to censor himself, "It's like the world's most fucked up personality test." John tips his face up to look at McKay without thought.

McKay's lips quirk at him; apparently he has no objection to being looked at. John feels his own lips quirk back. "So far, I've determined that you're a Masochistic Cock-sucking Smart-ass," McKay tells him seriously. "MCS's make up less than one percent of the population, you know."

"What are you?" John asks, genuinely curious.

"I'm not all that hard to figure out," McKay says modestly, eyes gleaming. "I'm your standard SGC: Sadistic Genius Control-freak."

"Genius, huh?" John murmurs.

"Astrophysics," McKay says with a sharp little smile. "Some day you'll be able to tell yourself you sucked the cock of a Nobel Prize winner."

"Someday soon?" John asks dryly, and McKay's hand in his hair goes hard, and John's head snaps back at the force of the yank. He hisses a little, and his cock jumps, and things snap back into place a little and he averts his gaze.

"Don't get ahead of yourself," McKay snaps, and John bites his lip against the urge to _apologize_. He is completely out of his depth, he realizes with something like surprise. This isn't what he went looking for, and he has no idea what to do with it. "Okay, forget word association," McKay says quietly. "These are yes or no questions." He uses his grip on John's hair to angle his face so that John's head is tipped so far back that he has to meet McKay's narrowed gaze. "You're clear on the concept that the fact that I'm asking you these questions in no way obligates me to take into consideration any of the answers, aren't you, John?"

"Yeah," John says, but he doesn't actually believe that. McKay, he's pretty sure, will not do anything at all without taking every one of John's answers into consideration.

"Good," McKay says, and lets go of John's hair. "Gags."

"Yes."

"Rimming."

"Yes."

"Swallowing."

"Yes."

"Watersports."

"Yes."

"Cockrings."

"Yes," John says tightly, and McKay gets down on one knee, elbow resting on the other, and pushes his thumb into the underside of John's jaw, forcing his face up. McKay's eyes are very blue.

"Orgasm denial."

"Yes," John says through clenched teeth.

"Blindfolds."

"Yes."

There's a pause. McKay looks at him very intently. "Full hoods."

"Yes," John says hoarsely.

"Full immobility."

"Yes."

"Electricity."

John hesitates -- he's never tried it, and has no real idea, but -- "Yes."

"Collars."

John swallows hard, but says, "Yes."

Another pause. Then McKay's voice is very quiet. "Humiliation."

"Yes," John manages from between clenched teeth.

"Pain." McKay asks, and presses a hand to the small of John's back again, warm and steadying.

John forces his eyes front and center, and says, "Yes."

The questions stop for a while, and John's jaw is aching where McKay's thumb is jabbed up under it, and he feels strung tight and breathless.

"What's a 'no,' John?' McKay murmurs, low and tight, and John's spine straightens instinctively even as his belly clenches.

"I-" John says, and swallows hard. "Scat," he says firmly. "Anything that leaves permanent marks." After several seconds, he adds, "Toys."

"Toys?" McKay sounds both amused and disbelieving. His hand falls away from John's jaw, and he stands up and circles around behind John.

John infuses his voice with as careless an edge as he can manage. "Dildoes," he says, "vibrators, beads, plugs."

When McKay speaks again, it's from right behind John. He can feel McKay's breath against this neck. "Nothing in your ass," he says, and John is opening his mouth to agree when McKay adds, "Except cock."

John closes his mouth slowly, face hot, cock hard, and doesn't disagree.

"Nothing fake," McKay continues, sounding thoughtful. "Nothing impersonal." McKay's lips brush against the back of his earlobe, and John shivers. "This is very personal for you." It doesn't sound like a question. "You don't do this often, do you?"

John swallows hard, but McKay says nothing for so long that he eventually shakes his head. One of McKay's hands cups his hip for a moment, then slides along the crease where his thigh meets his body, dipping between John's thighs to cup his balls. The other is still pressed to the small of John's back, holding him still. John makes a thick noise in the back of his throat, and McKay shushes him next to his ear.

This isn't what John had gone looking for tonight, _McKay_ isn't who he had _meant_ to find, but. He thinks it should be intrusive, uncomfortable, hearing things like this from a stranger's mouth, but it isn't. It's actually not even close to it. John feels... comforted. It feels. Safe. To be known.

John's chest hurts. He wants to leave. He wants to touch McKay's _pants_. He feels unmoored.

"Are you looking for substitute commanding officers, John?" McKay asks in a low, careful voice. At the same time, his hand goes tight around John's balls.

"No!" John hears himself half-shout, voice ragged and shocked, his balls aching in McKay's fist. He's squirming a little, helplessly moving into and then away from the bright pain; McKay's grip is implacable. "No," he repeats in a mumble, and shakes his head. He forces himself to take several breaths, rasping through clenched teeth, but his head clears a little, and he doesn't know what drives him to turn and look at McKay, to meet his eyes, but it feels right. McKay looks back at him, his expression curious and focused; his eyes are hot as they flick to John's neck and his mouth. It's easier than John expects to admit, "Something else. Something better than that."

"Hrm," McKay says, and leans forward abruptly to lick the sweat off of John's temple, tongue quick, lips lingering, his grip on John's balls going loose and caressing.

John shudders.

  
5.

"Let's go with Banach-Tarski as your safeword," McKay says almost absently; he's presses warmly against the right side of John's body, one hand on John's hip, his lips tracing lazily along John's hairline. John blinks.

"You want to go with a Euclidean geometric paradox for my safeword?" he asks, bemused.

McKay's hand digs abruptly into John's shoulder, turning him so that he gets a look at McKay's wide eyes, so utterly surprised he's like an entirely different person, cheeks flushed, lips curving into a smile that's almost sweet. "You're familiar with the Banach-Tarski paradox theorem?" he asks sharply, and his hand tightens down on John's balls, making John grunt with surprise.

"Sure," John gasps, and stares at McKay's sweet smile while he tries to reconcile it with his sharp voice and slowly-tightening grip on John's balls.

John's fingers twitch on his thigh; he wants to touch McKay's mouth.

"Give it to me," McKay demands, still smiling, still squeezing, and John starts to shake.

"Uh, it, uh states that it's possible to take an ordinary ball in 3-space, cut it up into finitely many subsets-" McKay lets go of his balls abruptly, and the heavy beat of blood and pain makes John hunch over, stealing his breath. Even as he gasps, McKay takes him by the shoulders and turns him. John relaxes deliberately, lets himself be loose and movable until he can feel McKay's worn cords against his ass and thighs (they're soft and interestingly textured, he discovers). McKay pushes his own thighs between John's to hold them open, tugs John back with an arm around his belly until John is straddling McKay's lap, his back resting along the length of McKay's chest. McKay slides a hand into his hair, tugging gently until John lets his neck go loose, lets his head fall back onto one of McKay's broad shoulders. John doesn't know what to do with his hands, so he leaves them loose at his sides and looks at the textured ceiling, waits to be told what to do.

"Okay," McKay says, voice low and rough; he curls his hand around John's balls again, squeezing until John hears himself make a gulping sound, until his hips jerk a little, helplessly. McKay stops tightening his fist but retains that pressure, and heat floods into John's face and neck as his cock jumps and his breath rattles in his tight chest. "Don't stop," McKay murmurs into his ear, his other hand sliding soothingly back and forth just above John's navel. John makes a hitching sound, he can't stop it, and McKay urges, "Finitely many subsets..."

"And, and reassemble them-" John manages, trying to think around his aching balls and the warmth of McKay's palm curving around the ribs on his left side, "-to make two, ah, two balls both congruent to the o-original." There's a triumphant thrill at actually finishing, so so strange, but it's good and it's nothing he's ever had, and he strains a little against McKay's grip, caught and _safe_ , and, "Ow," he whispers, and McKay chuckles against the side of his neck.

"Now the math, John," McKay says, and gives John's balls an impatient little jerk. "Give me the _equation_."

"If," John gasps, "If _G_ is a group acting on a set _X_ , and _X_ is an _n-_ dimensional Euclidean space, and _G_ consists of all isometries-" McKay bites his neck hard, bites and holds on, and makes a small soft sound of pleasure with John's flesh still caught in his teeth, and John says, "Please, of, God, God, of _X_ , and two subsets _A_ and _B_ of _X_ are _G_ -equidecomposable, then, then-" John has to stop and breathe, and McKay jerks John's head around by a handful of John's hair, and John finds himself looking McKay in the eyes, which are bright and hot and a little crazy-looking, and he leans in and bites at John's mouth, and John doesn't realize he's let go of John's hair until McKay's fingers close tight around his left nipple, twisting so hard that John's eyes sting. John's hips react mindlessly to the pain, jerking upward, pulling against McKay's hand around his balls so that he lets out a short, hoarse cry, muffled against McKay's lips and teeth. McKay laps gently at John's bottom lip and hisses impatiently,

"Go on, keep going."

McKay's hard on is pressed against his ass, and McKay's thumb is sliding gently back and forth across John's sore nipple, and he thinks, _Oh, please oh yes, I need_ , but he lets his head fall back onto McKay's shoulder and says, "This d-defines an equivalence relation among, among all subsets of _X_ ," all in a rush, hoarse and stumbling.

"It does," McKay whispers, "It really does," and he flicks his thumb across John's nipple one last time, and then slides his hand down John's belly, all the way down until John is hitching out hopeful little sounds of want. McKay's big, warm hand curls around John's cock and John's hips jerk, tugging against both of McKay's hard hands, and it hurts, his balls hurt, and McKay's hand on his cock is tight and perfect and it's so good John chokes out a desperate little sob. "Finish," McKay breathes against John's neck, wet mouth leaving cool patches on John's skin, and his arms are warm and close around John, holding him up and grounding him. "Finish it, and I'll finish you, John," McKay promises, and John has to bite his lip to keep from blurting _thank you, please, thank you_.

"McKay," he groans helplessly, and both of McKay's hands tighten until John's back bows and he's dizzy and desperate.

"I've got you, don't stop," McKay moans against his neck, and his hips describe a brief, hard ellipse, shoving his cock against John's ass, burning John's naked skin with the soft-sharp texture of his pants, and the want is aching and clear in McKay's voice, as if he sees no reason to bother with hiding it, and it does something sharp and hot in the center of John's brain and in the cradle between his hipbones and at the base of his spine.

"And if there are elements _g_ 1, through _g_ k of _G_ ," he tells McKay, and he thinks of McKay's hot eyes and his rough hands and the broad warmth of his body, "such that for each _i_ between _1_ and _k_ , if g _i_ of A _i_ equals B _i_ , then _A_ and _B_ are _G_ -equidecomposable-" He chokes into silence as the hand around his cock strokes slowly upward, base to head, McKay's thumb hooking skillfully across the glans to smear precome around the flared head of John's cock, and for several seconds he thinks he'll come, he wants to come, and shakes silently until McKay's hand goes still, and he rasps out, "-using _k_ pieces. And if a set _E_ has two disjoint subsets-" McKay's hand strokes him again, slower this time, and the hand around John's balls pulls gently, and John gasps, "-subsets, God, subsets _A_ and _B_ such that _A_ and _E_ , as well as _B_ and _E_ , are, are, oh oh, please, oh-" McKay's hand is jerking him hard and fast, John's balls are a tight, helpless knot of agony in McKay's fist, he wants to come, he wants to beg, and a helpless, needy sound tears its way out of John's throat as he shakes and twists against McKay's solid bulk.

" _G_ -equidescomposable," McKay whispers against the edge of John's ear while his fist mercilessly strips John's cock, and then, in a whisper, "Do this for me, John."

And John half-shouts, half-snarls, "And if a set _E_ has two disjoint subsets _A_ and _B_ such that _A_ and _E_ , as well as _B_ and _E_ , are _G_ -equidecomposable then _E_ is called paradoxical, _paradoxical_ , God, _Mckay_ , please!"

And McKay releases his balls and twists his palm fiercely around the head of John's cock, and the absence of pain is just as good, just as sweet, as the helpless, hopeless crush of pleasure, and John shakes apart, curling reflexively forward, but McKay holds him there, holds him still, hand drawing John's pleasure out, dragging him through aftershocks that ache and burn, until he's loose and quiet and dazed.

  
6.

"Oh my God," McKay groans, and releases John's cock abruptly. Johns gasps out a whimper, breath hitching a little in relief and protest and gratitude, and while his mouth is still open but his eyes are still closed, McKay slides a hand into John's hair tugs his head around, cradles the back of his head and kisses him, hot and wet and dirty, but slow, tongue fucking into John's mouth, but gently, and John's left nipple is throbbing and his balls feel bruised and tender and his cock jerks a little, as though presently spent but willing to telegraph its approval as best it can anyhow.

McKay pulls back, mouth wet and red, eyes searching John's face intently. His hand is still cradling the back of John's head. The other is pressed warmly to John's belly, heedless of the come cooling on John's skin. The position is awkward, makes John strain a little, which his body doesn't want to do after coming that hard, but John does it anyway. "Well, that won't work then," McKay tells him seriously, and John feels like his belly drops down to his toes. But then McKay says, "We can't make your safeword something we might actually want to talk about."

Something wells up thickly in John's throat, but his belly returns to its normal relative position, which he thinks is good.

"How do you feel about Russian literature?" McKay asks, and then looks momentarily worried. "Please tell me you aren't a literature nerd, too; the math makes up for a lot, but-"

John is surprised to discover that the something thick in his throat is a _laugh_.

McKay smirks as though he understands the choked, amused sounds John is making, and the hand cradling the back of John's head slides down to curl around the back of his neck instead. "What do you think of Tolstoy?"

"He's dead," John says. His voice is wrecked, hoarse and unsteady and a little slurred, still suffering from the after-effects of what was probably the best orgasm of his life (from nothing but McKay's hands and his voice). "Dead and boring," he adds.

McKay makes a soft sound in the back of his throat that makes John feel too warm, and reminds him that McKay hasn't come yet. "That'll do, then," McKay says, and stands up so suddenly that there can't be any doubt that at least some of the purpose of it was to make John sprawl forward onto his hands and knees, which he obligingly does. When he looks up, McKay is dragging his t-shirt off over his head, and giving John a slow, appraising once-over. While he does both of these things, he snags his beer and tips it back, draining the rest of the bottle in several long swallows. John stays where is he is, splayed a little uncomfortably, his hands and knees spaced awkwardly so that they don't really support his weight evenly, and watches McKay's throat as he swallows and wonders at other ways that he might be able to multi-task. The warm want is already twisting low in his belly again, though it'll probably be a little while before his cock catches up to it.

McKay thumbs the button of his cords open and sets the empty bottle aside. John can see the outline of his cock. It looks long and thick and John wants it.

"I'm going to do something on your very short 'no' list, John," McKay says, smirking a little, voice faintly smug. John feels the tension click into place in his brain, but his body doesn't follow. He doesn't know if it's because he's really that relaxed, or if it's something else. McKay takes a couple of steps closer, until John has to crane his neck uncomfortably to look up at him. "I'm going to make you like it," he says almost gently.

John bites his lip and lets his neck unbend, looks at the carpet and says nothing.

"I told you I wasn't obligated to take any of your answers into consideration," McKay reminds him, and toes John in the ribs.

John looks up obligingly; McKay's looking narrow-eyed and impatient. "You're considering all my answers," John says simply. "You'll do whatever you do because of them, or in spite of them, but not without considering them."

McKay arches a brow at him, but he smiles a little. "You're absolutely right." He hooks his thumbs into either side of the waist of his pants and shoves them down, steps out of them with one foot, and uses the other to kick them away. John looks at him and wants him, maybe more than he's ever wanted anything except to fly. "It's incredibly hot that you're not a moron. Come here and suck me."

  
7.

Later, when John is splayed face down on the enormous bed, tied belly down with actual rope (McKay tells him, as he carefully, systematically coils and loops and knots, that he likes rope rather than anything quicker because knots are just solid math), McKay shows him a brutally thick dildo the circumference of John's wrist, makes him do the math, so he'll know. McKay rubs lazily against John's hip and murmurs, "You were like a black stiletto in a room full of blunt objects, John."

"No," John says, "no," and lays still while McKay slides slick fingers into his ass, presses the wide, blunt tip of the thing against his hole. "No," he whispers when it begins to open him, and McKay kisses the side of John's sweaty face, and strokes a soothing hand down John's spine while John makes helpless choking sounds at the feel of being opened by cool, slick rubber.

McKay whispers, "Half the people there were trying to stay out of your way and the other half were trying to get your attention. You looked like you were the predator. I don't think most of them knew what to think of you. I wanted you the second I saw you."

"No," John whispers, "no, please, no," as McKay slowly, mercilessly pries him open, works the dildo into him until John is full and spread and pinned by it.

McKay kisses John's shoulder, his neck, the top of his ear, murmurs ceaselessly, low and hard and thick, "You're beautiful, John. You're perfect; give me this, John. I want it," and fucks him and fucks him and fucks him until John's groans are cracked and ceaseless, and eventually it's just his name, just, "John, John, John," while John writhes and whispers, _please_ , and _no, no more_ , and _McKay_.

"I-" McKay presses his lips to John's earlobe to whisper, his cock hard and wet against John's hip, "I want you open like this, I want you loose and sweet and easy for my cock, John," and John sobs, low and hoarse and broken, and comes helplessly against the bedspread.

  
8.

McKay orders room service sometime in the small hours of the morning. He feeds John french fries drowned in catsup and sticky bites of waffles and cubes of sharp cheese. John half-drowses between bites and flexes his fingers occasionally to make sure they aren't going numb. McKay makes moaning orgasm noises while he eats cheesecake and slurps his coffee disgustingly.

John is tired and loose and absolutely content; he falls asleep to the sound of McKay using a laptop at the desk.

He wakes up in the dark as McKay's hands move searchingly over him, checking the knots and to be sure John's hands aren't cold from circulation-related problems. "They're fine," John husks softly in his newly cracked voice, and McKay goes still for a few seconds.

Then he touches John's mouth.

"You're on leave," McKay says to him. His voice is tight and a little flat.

"Yeah," John agrees, and turns his face to press it against McKay's shoulder, which is the only place he can really reach.

"Stay with me," McKay tells him, something that wants to be a demand, but is too raw and sincere for that. "Stay until you... Until you have to go."

John presses his face hard against McKay's shoulder, chest so tight he can barely drag in enough air to answer. "Yeah," he whispers. "Okay."

  
9.

John stays for eleven days.

John doesn't leave the hotel. They order all their meals from room service or a Thai place McKay knows that will deliver anywhere. John spends forty-one hours in a row tied to the bed, excepting bathroom breaks. McKay gives him a sponge bath. A small mountain of towels grows on the bathroom floor, until a harried floor manager calls the room and asks if they'll please give some of them back. McKay dumps them all on the floor in the hall.

Sometimes McKay leaves for a couple of hours. Usually he comes back with fresh towels or more lube or nipple clamps, but John doesn't think those things are the actual reason he goes. Sometimes he works on his laptop. Sometimes he locks himself in the bathroom, and John can hear him yelling at people on his cell phone.

Usually it makes him hard.

John blows him once when he's on a conference call.

Forty-eight hours before John has to be on a military hop, John tells McKay he has twenty-four hours left. He's pretty sure he's going to need some time, after.

McKay goes still and silent. He's just come out of the shower, and his hair is sticking up in wet little clumps. He rubs at it absently with a towel, and John watches him process, his eyes internally focused, a vertical line deepening between his eyebrows. Almost hesitantly, he begins, "You could-"

"No," John stops him. "I couldn't." Because he knows it isn't just him, so he was expecting it.

McKay's face folds into a scowl.

"I'm an officer in the United States Air Force," John tells him, hard and flat and a little angry, even though he isn't angry. Not even a little.

"Oh, if this is about _patriotism_ -" McKay snaps, and John cuts him off again.

"I'm a fighter pilot, McKay. I fly combat jets and helicopters." John watches him process that, watches him understand it, and says, "I have to go back." He doesn't add _I have to fly_ because McKay already knows that. John had told him over three excruciating hours, blindfolded and immobilized and tethered to the world by nothing but McKay's voice in his ear, _"Tell me about flying, John, tell me how it feels."_

McKay's mouth goes flat and unhappy, but he doesn't argue. He drops his towel on the floor and strides naked toward him, and McKay isn't a fighter, so every shift of his body telegraphs his intent, but John doesn't even twitch to avoid the backhand, which catches him high across his right cheek. Pain explodes behind his right eye; McKay is broad and strong, and John reels backward two staggering steps and goes down.

It isn't the first time McKay has hit him. John has bruises scattered across his back and ass, a few high up on the insides of his thighs. Most are from John's own belt, a few from a doubled over length of rope. He's slapped John a few times, strong and solid blows that left John's ears ringing and his cock aching.

John is okay with pain, and McKay had made no bones whatsoever about his own sadism.

It doesn't even hurt all that much, once John's vision clears.

But his chest is tight, and McKay's mouth is pulled down on one side, his eyes hard and bright with pain. He slaps John open-palmed while John is still reeling on his knees, and John falls forward and catches himself on the floor with the heels of both hands. McKay fists a hand in his hair and jerks him upright, and slaps him again. John's lip splits and his eyes sting and leak, and his chest is still tight and aching when McKay takes him by the shoulders and shoves him onto his belly on the carpet, pinning his hands above his head and shoving his cock into John in one hard, sharp thrust. John is still a little wet and loose, but not enough, and he shouts into the curve of his biceps and spits blood onto the carpet when he bites his tongue to go with his split lip. McKay doesn't slacken, fucks him hard and sharp and doesn't bother with John's prostate, punishes John with his cock until John is loose and pliant beneath him, and then he shudders and bends to press his forehead between John's shoulder blades and comes in absolute silence.

John's cock is hard and neglected, and carpet burned. There are tears and blood on his face, and he doesn't want to go. He never wants to go.

McKay lets go of his wrists to flip him onto his back and strains to one side to grab something beside the bed. John whines when McKay pushes the dildo into him, the thick one that means he isn't playing, and throws an arm over his face. "Don't even think about it," McKay hisses, and reaches up and jerks John's arm away from his face, shoves it above his head. "Let me see," he sneers, and wraps a hand around John's cock roughly, pushes the dildo into him sharply, angled perfectly ( _"Physics,"_ he had told John once, before, eyes wide and bright with amusement, _"is the key to the mysteries of the universe, John."_ ), and John bites back a cry that wants to be a scream, thighs going loose and open for McKay, and McKay jerks his cock twice, three times, dildo moving in perfect counter-point. "John," he says hoarsely.

"God," John moans, high and urgent and needy, whole body tight and tender, riding up desperately into McKay's hand, helplessly open and horribly unfettered. "Please, I, McKay, please, please, I- I-"

"I know," McKay tells him, low and brittle and _grieved_. "I know, _John_."

McKay's voice breaks on John's name, and John comes and comes, shuddering. McKay bends and slides his mouth over the head of his cock to catch the last weak pulses, and John sees his mouth, wet and stretched around John's cock, hot tongue like razor blades on the tender head, and comes again, painfully, empty nuts clenching and tight, until he's whimpering and shaking and hollow on the floor, McKay's big hands cupped around his hips, his forehead resting low against John's belly.

McKay half carries him to the bed sometime later, John limp and exhausted and staggering, wipes him down with a warm, wet cloth, hands careful and gentle getting the blood off his face. He's familiar with John, after, at this point, and he tells John about the guy he made cry at a conference in Geneva last year, rips string theory into its component pieces, answering all of John's slurred questions with sarcastic patience, since they both know it's pretty much over John's head and he's only asking to hear McKay talk, and because he's McKay, right around the time that John is starting to drift on the cusp of sleep, McKay asks the things he really wants to know.

Sometimes John answers these questions. Sometime he pretends he's asleep.

This time it's, "How did you break your nose, John?" while he rests a fingertip against the bump at the bridge of John's nose. John turns his head and smushes his cheek against McKay's hairy thigh.

"Horseback riding," he slurs. "Was nine."

McKay makes a quiet, thoughtful sound. "How long have you been in the Air Force?"

"Eight years," John tells him, and McKay runs gentle fingers through his hair as a reward.

"Where did you go to college?"

"MIT," John says, and smiles tiredly at the choked and indignant noise McKay makes. "'m smart," he sighs.

McKay snorts. He's quiet for a while, hand petting absently from John's crown to the middle of his spine. John is warm and loose and comfortably achy. "What's your last name," McKay eventually whispers, as though willing to not be heard if John is asleep.

John only really thinks about it for a moment. "Sheppard," he whispers back, and opens his eyes to look at McKay. "Captain John Sheppard, USAF."

McKay's hand curls possessively around the back of his neck, and he quirks a crooked smile at John that is both genuine and awful to look at. "It's nice to meet you," he says.

"You, too, Rodney," John says thickly.

  
10.

  
In the PX, John idles while he waits for his plane. Flipping through a bargain book rack, he finds War and Peace. It's a cheap book club edition, probably bulk leftovers donated to "the troops overseas," but it's in hardback, and it'll probably hold up to John's duffel, so he buys it anyway.

He ends up taking it to five continents.

John keeps the slim white card McKay gave him. He tucks it into his wallet behind his social security card.

He's flown combat his whole career, so his affairs are always in order. John's left instructions donating whatever is in his bank account to a scholarship for prospective pilots, and his personal possessions are to go to his ex-wife. The Air Force is a little squirrelly about having someone to notify, and out of everyone there is, she's the one John figures gives a shit, at least a little.

One day, while he's fairly drunk, he takes the card out of his wallet and writes, "notify in the event of death" above McKay's name on the card. He stares blurrily at it, and adds, "send dogtags, flag." It won't hold up in court, and it won't do anything at all if he's MIA or his body isn't recovered, but. He leaves it anyway.

He Googles McKay a few times. Mostly he finds older stuff, papers published and seminars he'd lectured at. It's all from around the time John had met him, or earlier. His driver's license expires, and isn't renewed.

It's like he fell off the face of the Earth.

Once, when he's in the area, he walks by the club where McKay had picked him up.

He doesn't go in.

 _  
**SG:A Fic**   
_

**Author's Note:**

> Thanks go to the usual suspects, [](http://cindyjade.livejournal.com/profile)[**cindyjade**](http://cindyjade.livejournal.com/) and [](http://the-drifter.livejournal.com/profile)[**the_drifter**](http://the-drifter.livejournal.com/), for all the usual reasons, and also to [](http://pir8fancier.livejournal.com/profile)[**pir8fancier**](http://pir8fancier.livejournal.com/) for the last minute beta, for she is the awesome. This was, probably not surprisingly, spurred into existence by Kink!Bingo, but I'm choosing not to use it for that for a couple of reasons. Nevertheless, a thank you to the ladies responsible for Kink!Bingo is in order. THANK YOU!! Also, people who do Math: I translated an equation from Math to English for the purposes of this story, and it is probably wrong wrong wrong. Feel free to help me correct it, but if you do, you're enslaved as permanent Math-Beta until the end of time. <3


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